This invention relates to copolyesters derived from p-dioxanone, and especially to such crystalline copolyesters having mechanical and biological properties which are desirable for the preparation of absorbable surgical sutures.
U.S. Pat. No. 4,052,988 describes p-dioxanone homopolymers and the preparation of absorbable filaments exhibiting mechanical and biological properties suitable for use as surgical sutures. Unlike previous absorbable synthetic sutures developed, for example sutures derived from homopolymers of lactide or copolymers of lactide and glycolide, p-dioxanone sutures can be used as a monofilament because of their enhanced flexibility and pliability. Conventional synthetics require a braided or twisted construction in a multifilament form in order to reduce the "stiff" feel of the suture. Unfortunately, multifilament sutures are often disadvantageous because their rough surface can often tear tissue during operative procedures.
As good as the sutures derived from p-dioxanone are, there is still room for improvement. U.S. Pat. No. 4,643,191 describes copolymers of p-dioxanone and lactide, and absorbable sutures prepared therefrom. The lactide component of the copolymer may offer enhanced physical properties, for example, increased straight or knot tensile strength and reduced modulus, without sacrificing any of the other outstanding properties of a p-dioxanone homopolymer.
U.S. Pat. No. 4,653,497 describes absorbable sutures prepared from copolymers of p-dioxanone and glycolide. The glycolide component of the copolymer significantly increases the rate of in vivo absorption and the in vivo breaking strength retention properties of the copolymer, properties which can be extremely advantageous for certain operative procedures.
In view of the attempts described in the art to modify or enhance the properties of p-dioxanone homopolymers, it would be desirable to formulate a polymer composition which can offer the possibility of creating flexibility in the biological properties attained without sacrificing mechanical properties.